Atmospheric River Variability Over the Last Millennium Driven by Annular Modes

Baek, Seung H.; Battalio, J. Michael; Lora, Juan M.

doi:10.1029/2022av000834

Cited by 4 publications

(8 citation statements)

References 89 publications

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“…Following ( 23 , 60 ), AR frequencies are calculated as the percentage of 6-hourly time steps in which an AR is detected divided by the total number of 6-hourly time steps in the specified analysis period. Following ( 63 ), AR durations are calculated as the continuous length of time that a given location is experiencing AR conditions (i.e., is located within the spatial extent of an AR defined by the AR tracking method). AR intensity is inferred from the average IVT of AR conditions at a given location.…”

Section: Methodsmentioning

confidence: 99%

“…), CENP (20°N to 45°N, 110°W to 140°W), SCNP (10°N to 20°N , 180°W to 140°W), and SENP (10°N to 20°N, 100°W to 140°W). ARs are identified in the North Pacific and SWNA regions using an automated tracking method that has previously been used in paleoclimate studies (7,23,(61)(62)(63). We define ARs as contiguous regions of at least 2000 km where 6-hourly (instantaneous) vertically IVT exceeds a threshold value.…”

Section: Experimental Designmentioning

confidence: 99%

“…Following (63), AR durations are calculated as the continuous length of time that a given location is experiencing AR conditions (i.e., is located within the spatial extent of an AR defined by the AR tracking method). AR intensity is inferred from the average IVT of AR conditions at a given location.…”

Section: Experimental Designmentioning

confidence: 99%

See 2 more Smart Citations

North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

Oster,

Macarewich,

Lofverstrom

et al. 2023

Sci. Adv.

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Atmospheric rivers (ARs) bring concentrated rainfall and flooding to the western United States (US) and are hypothesized to have supported sustained hydroclimatic changes in the past. However, their ephemeral nature makes it challenging to document ARs in climate models and estimate their contribution to hydroclimate changes recorded by time-averaged paleoclimate archives. We present new climate model simulations of Heinrich Stadial 1 (HS1; 16,000 years before the present), an interval characterized by widespread wetness in the western US, that demonstrate increased AR frequency and winter precipitation sourced from the southeastern North Pacific. These changes are amplified with freshwater fluxes into the North Atlantic, indicating that North Atlantic cooling associated with weakened Atlantic Meridional Overturning Circulation (AMOC) is a key driver of HS1 climate in this region. As recent observations suggest potential weakening of AMOC, our identified connection between North Atlantic climate and northeast Pacific AR activity has implications for future western US hydroclimate.

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Section: Methodsmentioning

confidence: 99%

Section: Experimental Designmentioning

confidence: 99%

See 1 more Smart Citation

North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

Oster,

Macarewich,

Lofverstrom

et al. 2023

Sci. Adv.

Self Cite

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“…In the present day, these regions are heavily influenced by atmospheric rivers (ARs), synoptic plumes of water vapor that account for the majority of atmospheric moisture transport and are associated with extreme precipitation (high intensity precipitation events; Dettinger et al., 2011; Guan et al., 2010; Lamjiri et al., 2017; Lavers & Villarini, 2013; Ralph et al., 2019; Waliser & Guan, 2017; Zhu & Newell, 1998). Yet modern‐day ARs occur across all of the extratropics in close connection with the storm tracks (Baek et al., 2023; Lora et al., 2020; Newman et al., 2012; Shaw et al., 2016; Sodemann & Stohl, 2013; Viale et al., 2018; Zhang et al., 2019; Zhu & Newell, 1998); therefore, whether and to what extent LGM ice sheet and other forcings alter the behavior of ARs globally is our primary interest. A companion study (Skinner et al., 2023) investigates the influence of ARs on the LGM ice sheets themselves; our focus here is on the unglaciated mid‐latitudes.…”

Section: Introductionmentioning

confidence: 99%

The Hydrologic Cycle and Atmospheric Rivers in CESM2 Simulations of the Last Glacial Maximum

Lora,

Skinner,

Rush

et al. 2023

Geophysical Research Letters

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Proxy reconstructions and model simulations of precipitation during Earth's glacial periods suggest that the locations and mechanisms of atmospheric moisture transport have changed considerably during Earth's past. We investigate the hydroclimate of the Last Glacial Maximum (LGM) using simulations with the Community Earth System Model, with a focus on the extratropics and the influence of atmospheric rivers (ARs), a key driver of modern‐day moisture transport globally. Mean and extreme precipitation increase significantly over southwestern Patagonia, Iberia, and southwestern North America—mid‐latitude regions affected by ARs in the modern climate—despite overall decreases elsewhere. In each, the associated moisture transport changes are different, with increased transport and AR activity mainly occurring in the North Atlantic. The overall LGM response is dominated by the response to ice sheets, with other forcings causing additional cooling and drying over the extratropics and a strong decrease of moisture transport over the subpolar North Atlantic.

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“…They can lead to extreme events including extreme precipitation (Ma et al., 2020), extreme wind events (Waliser & Guan, 2017) and flooding (Leung & Qian, 2009), particularly along the western coasts of North America and Europe. Recent studies show that anomalies in the strength of stratospheric polar vortex can influence the frequency of ARs and the associated precipitation through an anomalous tropospheric jet (Baek et al., 2023; Lee et al., 2022; Ma & Chen, 2022). However, given the distinct planetary wave mechanism and surface impacts, the potential influence of extreme stratospheric wave events on ARs remains elusive.…”

Section: Introductionmentioning

confidence: 99%

Stratosphere‐Troposphere Coupling of Extreme Stratospheric Wave Activity in CMIP6 Models

Ding

Chen

2023

JGR Atmospheres

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Extreme stratospheric wave activity has been suggested to be connected to surface temperature anomalies, but some key processes are not well understood. Using observations, we show that the stratospheric events featuring weaker‐than‐normal wave activity are associated with increased North American (NA) cold extreme risks before and near the event onset, accompanied by less frequent atmospheric river (AR) events on the west coast of the U.S. Strong stratospheric wave events, on the other hand, exhibit a tropospheric weather regime transition. They are preceded by NA warm anomalies and increased AR frequency over the west coast, followed by increased risks of NA cold extremes and north‐shifted ARs over the Atlantic. Moreover, these links between the stratosphere and troposphere are attributed to the vertical structure of wave coupling. Weak wave events show a wave structure of westward tilt with increasing altitudes, while strong wave events feature a shift from westward tilt to eastward tilt during their life cycle. This wave phase shift indicates vertical wave coupling and likely regional planetary wave reflection. Further examinations of CMIP6 models show that models with a degraded representation of stratospheric wave structure exhibit biases in the troposphere during strong wave events. Specifically, models with a stratospheric ridge weaker than the reanalysis exhibit a weaker tropospheric signal. Our findings suggest that the vertical coupling of extreme stratospheric wave activity should be evaluated in the model representation of stratosphere‐troposphere coupling.

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Atmospheric River Variability Over the Last Millennium Driven by Annular Modes

Cited by 4 publications

References 89 publications

North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

North Atlantic meltwater during Heinrich Stadial 1 drives wetter climate with more atmospheric rivers in western North America

The Hydrologic Cycle and Atmospheric Rivers in CESM2 Simulations of the Last Glacial Maximum

Stratosphere‐Troposphere Coupling of Extreme Stratospheric Wave Activity in CMIP6 Models

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